A computed tomography (CT) system is described in DE 10 2005 041 538 B4. The known CT system includes a stationary part and a rotatable part that is supported rotatably in the stationary part. Disposed in the rotatable part are at least one x-ray tube unit cooled by a cooling fluid and an x-ray detector lying opposite the x-ray tube unit and also a cooling device coupled in terms of fluid technology via a cooling circuit to the x-ray tube unit. Disposed in the stationary part is a cooling air channel through which cooling air is able to be fed into the rotatable part. Furthermore, an exhaust air channel is disposed in the stationary part, through which the heated exhaust air is able to be discharged from the rotatable part.
The x-ray tube unit has a tube unit housing in which an x-ray tube is disposed. The x-ray tube includes a vacuum housing in which a cathode and an anode are disposed. The heat arising during the creation of the x-ray radiation within the x-ray tube is primarily taken up by the anode. The x-ray tube therefore has heat removed from it during operation by a circulating cooling fluid (e.g., oil or water). If, in this situation, a fracture occurs in the vacuum housing, cooling fluid reaches the hot anode and within a few seconds a large amount of steam may arise from the overheated cooling fluid. In order to overcome such a malfunction, collection containers and balancing containers are provided with air-cooled CT systems. This provides that a larger installation space is necessary and the constructional outlay is increased accordingly.